Aleuroctarthrus, Martin, 2008

Martin, Jon H., 2008, A revision of Aleurodicus Douglas (Sternorrhyncha, Aleyrodidae), with two new genera proposed for palaeotropical natives and an identification guide to world genera of Aleurodicinae, Zootaxa 1835 (1), pp. 1-100 : 51-52

ALEUROCTARTHRUS gen. nov.

Type species: Aleurodicus destructor Mackie, 1912: 142

DIAGNOSIS.

PUPARIA (Figs 90-93) – characters of most diagnostic importance are given in bold. As interpreted here, Aleuroctarthrus is defined by the following combination of characters: margin almost smooth, or with very shallow marginal crenulations (Fig. 90); 12 pairs of submarginal setae present (including the nominal caudal pair); 4 pairs of tiny submedian cephalothoracic setae and pair of 8 th abdominal setae, present; anterior marginal setae absent; submargin and/or dorsal disc sparsely provided with tiny simple pores of one type only (sometimes appearing loculate and sometimes appearing to have a minute central spine); cephalic pair and 6 abdominal pairs of subdorsal compound pores present, each with an acute axial process (Fig. 92), but these processes often not evident (see discussion, below); all abdominal compound pores very large and subequal in size, much larger than the cephalic pair; abdominal compound pore pairs located on segments III-VIII (as in Aleurodicus , see Fig. A); two pairs of cicatrices present on thoracic area (scars of third-instar compound pores); with only two large lingular setae (Fig. 91) (sometimes with two very small additional setae visible under 400X magnification); lingular apex excluded beyond vasiform orifice. Ventrally, each leg very large and with an apical claw (Fig. 90); antennae very long, reaching at least to middle legs; underlying abdominal segment VII / VIII boundary (between operculum and fourth abdominal pair of compound pores) is a pair of circular secretory glandular areas (Figs 90, 93), each comprising subcircular cells (often with secreted material somewhat obscuring the structure, and the diaphanous nature of the ventral cuticle often leads to displacement). [2nd-instar with 3 pairs of compound pores, on cephalus, prothorax and last abdominal segment; 3rd-instar with 3 pairs of cicatrices in same positions.]

ADULTS – with eight-segmented antennae; antennae of males not provided with numerous prominent sensoria; abdominal wax plates numbering four in females and three in males, the posterior two pairs in females with stout setae along their anterior edges. Wings clear, unpigmented.

ETYMOLOGY. The chosen name reflects the characteristic eight-segmented antennae.

COMMENTS. The suite of characters given in bold, above, serve to define this new genus and to distinguish it from Aleurodicus and Palaealeurodicus . The antennae of adults of both sexes comprising eight segments is a character thought to be unique amongst known whiteflies, and is a major factor in proposing a separate genus. The presence of four abdominal wax plates in females, but only three in males, is a character shared with Aleurodicus but distinguishes Aleuroctarthrus from Palaealeurodicus whose known males possess four pairs of abdominal wax plates. Of particular note in the puparium are the presence of leg claws, presence of 12 pairs of submarginal setae and presence of submedian cephalothoracic setae (characters absent in Palaealeurodicus ). The reduction of puparial lingular setae to only one stout pair distinguishes this genus from both Aleurodicus and Palaealeurodicus , but this reduction in lingular setae is seen in some other Old World aleurodicine genera ( Pseudosynaleurodicus Gillespie , Stenaleyrodes Takahashi , Synaleurodicus Solomon ). The dearth of dorsal simple pores distinguishes Aleuroctarthrus from almost all Aleurodicus species.

The decision to propose a new genus to accommodate only a single species was taken reluctantly. However, it has long been clear that Mackie’s species destructor possesses characters that set it apart from the New World assemblage of Aleurodicus species , but which it does not share with any of the other palaeotropical aleurodicine taxa.

One further species, Palaealeurodicus indicus (Regu & David), has proved difficult to place generically, especially in the absence of adults and earlier-instar nymphs, because it shares some puparial characters with A. destructor (12 pairs of submarginal setae, margin smooth-to-irregular, ring-shaped compound pores, see figure 81), that are not shared by the other species of Palaealeurodicus . It is hoped that adults and 2nd & 3rdinstar nymphs of indicus might eventually provide some clarification, but indicus (see p. 50) is here placed in Palaealeurodicus based on other characters.